Determing Fault Location Within an Active Rift Basin Using Gravity Analysis to Determine Fault Movemnet and Effect on Water Recharge

Mark Andrew Ornelas, University of Texas at El Paso

Abstract

The growth of the El Paso, TX and Ciudad Juárez, Chihuahua, metropolitan area has increased reliance of groundwater pumping from the Hueco Bolson. With growing demands for water and recharge of the bolson not occurring at a fast enough rate, water storage within the bolson is beginning to diminish. My study focuses on locating and understanding how faults interact with water flow into the basin and how they aid in storing water on the northwestern side of the bolson. Previous studies in the northernmost part of my study area have delineated a series of faults that predominantly trend northwest-southeast. In the east central part of the study area on undeveloped portions of Ft. Bliss these mapped faults begin to curve and strike north-south. Other geophysical studies in the southwest and central portions of the study area have also inferred several north-south trending faults. Gravity has shown to be a very effective geophysical method for determining fault locations in an urbanized area, and was collected with 100-500 meter spacing in areas close to the mountains where most recharge occurs and a large data gap occurs. A better determination of the fault geometry of the Hueco Bolson is crucial to understanding ground water recharge and movement within the bolson. I used the existing and newly collected gravity data, in conjunction with water well information, to analyze the relationship between fault systems and freshwater recharge and movement. In conclusion, my results displayed a strong correlation between the gravity analysis and the geochemistry of the water wells in the area. The deepening of the Hueco Bolson is still the primary factor for the diminishing water quality but the faulting creates a compartmentalization effect based on the geochemistry and gravity analysis. This compartmentalization effect, creates zones of varying water quality between north-south running faults and heading eastward the water quality decreases. Between each set of faults the wells display similar water quality and seem to be consistent in the southern and central area. The water in the northwestern part of the study are tends to be of poorer quality likely due to the stepping over of the East Franklin Mountain Fault (EFMF)^

Subject Area

Geophysics

Recommended Citation

Ornelas, Mark Andrew, "Determing Fault Location Within an Active Rift Basin Using Gravity Analysis to Determine Fault Movemnet and Effect on Water Recharge" (2018). ETD Collection for University of Texas, El Paso. AAI13424417.
https://digitalcommons.utep.edu/dissertations/AAI13424417

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